Uninstall

My friend has a Viper car alarm in his 92' ford explorer. Its about 1 year old. He doesnt know the model number. He needs to uninstall his alarm but everyone wants to charge alot of money for this. How hard is it to uninstall these? I have done car audio installs but never an alarm install. Can someone help me with this? Can we take it out or is it best to just pay to get it removed?